Network security management is becoming a more difficult problem as networks grow in size and become a more integral part of organizational operations. Attacks on networks are growing both due to the intellectual challenge such attacks represent for hackers and due to the increasing payoff for the serious attacker. Furthermore, the attacks are growing beyond the current capability of security management tools to identify and quickly respond to those attacks. As various attack methods are tried and ultimately repulsed, the attackers will attempt new approaches with more subtle attack features. Thus, maintaining network security is on-going, ever changing, and an increasingly complex problem.
Computer network attacks can take many forms and any one attack may include many security events of different types. Security events are anomalous network conditions each of which may cause an anti-security effect to a computer network. Security events include stealing confidential or private information; producing network damage through mechanisms such as viruses, worms, or Trojan horses; overwhelming the network's capacities in order to cause denial of service, and so forth.
A variety of intrusion detection programs have been developed to detect and protect against threats to network security. As is known in the art, a common method of detecting these threats is to use a scanning engine to scan for known attacks against networked computers. These attacks can be identified by their unique “attack signature” which generally consists of a string of binary or text data. Upon the detection of an attack signature by the scanning engine, protective measures can be taken, including: sending alerts; intercepting harmful traffic; or disconnecting users who launch attacks.
Such intrusion detection programs are often positioned on a network to monitor traffic between a plurality of network devices. In use, a network administrator may set a sensitivity of an intrusion detection program which dictates a degree of certainty required before an event is determined to be a threat. In other words, by setting the intrusion detection program sensitivity low, fewer benign events will be misidentified as attacks, but the amount of actual attacks that go undetected may increase. On the other hand, by setting the intrusion detection program sensitivity high, more potential attacks will detected, but the amount of work required to differentiate between the misidentified events and actual attacks increases.
There is thus a need for a technique to decrease the workload of a network administrator by reducing the number of potential attacks which must be ascertained as actual attacks, while preventing any actual attacks from going undetected.